What is going on when someone (I assume just one person) suddenly goes through a bunch of my answers and upvotes all of them? For what purpose?
As a new user I sometimes did the same, when I saw a great answer by a user I was not yet familiar with. Chances are that the same user has written a lot of other great answers on similar topics, and reading them can be educational.
After a while it gets boring, and you tend to recognize most high-rep users. You also learn about serial down- and up-voting, and the bots/mods/machines searching for it.